Landfill methane emissions are worse than we thought

Hey there,

And then it was May!

Today, I’ll syndicate another piece I co-authored with Lauren Singer for The Overview, a biweekly dispatch on the world of methane and other super pollutants. In this edition, we cover methane emissions from landfills, the third-largest anthropogenic source. It got a lot of love and attention, so I figured I’d send it y’all’s way as well. Enjoy.

DEEP DIVE

The top line

Methane in landfills is generated from anaerobic conditions inside landfills, where methane-producing bacteria break down the waste and generate methane. Globally, landfills and wastewater contribute approximately 20% of anthropogenic methane emissions. This places landfills behind agriculture (~40% of human-caused emissions) and the oil and gas sector (35%) in terms of total contribution. 

Now, new satellite data is revealing that landfills consistently underreport their methane emissions—often by significant margins. According to recent research from satellite monitoring company GHGSat, methane is leaking from landfills at higher rates and more consistently than other major emitting sectors. Their analysis of 13 U.S. landfills found that nine were underreporting their methane emissions.

Importantly, unlike periodic, maintenance-related emissions typical in the oil and gas sector from things like pipeline leaks, landfill methane leaks are often persistent and widespread across facilities. That makes them more attractive for capture, a well-established practice at some facilities. There are proven technologies, approaches, and business cases (not to mention extensive existing infrastructure) for landfill gas capture that can transform this problem into a valuable resource, generating revenue while reducing emissions.

The data doesn't lie: landfills are major methane emitters

In addition to the GHGSat study, another study published last year found that landfills emit methane at nearly 3x the rate reported to federal regulators. The researchers measured emissions at roughly 20% of the 1,200 large, operating landfills in the United States, providing one of the most comprehensive direct measurement studies to date.

As noted in WasteDive’s coverage of GHGSAT’s findings, what's particularly concerning is that waste facilities had the highest site emissions rate:

“But the waste sector had the highest site emissions rate — on average, waste facilities emitted 1,250 kilograms of methane per hour, compared to 245 kilograms per hour in the oil and gas sector. The waste sector also had the highest persistence rate, at 69%, meaning ‘detected emissions from landfills were larger and more likely to be observed repeatedly across multiple satellite passes,’ per the report.”

Additional research by Arizona State University and Carbon Mapper from 2024 discovered that landfill emission plumes are remarkably persistent. 52% of surveyed landfills have high-point source emissions exceeding 100 kilograms per hour.

As we’ve seen and written about concerning several methane emission sources, traditional modeling approaches (estimations) used by the EPA and other regulators can systematically underestimate methane emissions from landfills. As Riley Duren, founder of Carbon Mapper and former NASA engineer, put it:

The business case for landfill gas capture

While the environmental imperative for reducing landfill methane is clear, there's also a compelling business opportunity at hand here. GHGSat's analysis of five U.S. landfills found that capturing methane to produce natural gas could generate more than $1 million in revenue per site annually. This aligns with the interests of several major waste management companies, including giants like Waste Management (almost $100B in enterprise value, traded publicly under $WM), who already employ landfill gas capture and other approaches to reduce methane emissions, though they could do much more.

What’s important to reiterate here is that the landfill waste sector offers perhaps the best landfill capture opportunity, which can be a high-leverage, cost-effective methane abatement measure. Many strategies could likely be implemented at little to no net cost after initial capex costs are discounted and the future value of the captured gas is appropriately accounted for.

The most commercialized approaches today include:

1. Landfill gas capture: Capturing methane and refining it to make natural gas, preserving methane’s value on Earth and keeping it out of the atmosphere is ideal, though it requires additional infrastructure capex. Captured methane can be processed to remove impurities and then used to generate electricity or heat, either on-site or off-site. This reduces emissions and provides a renewable energy source that displaces fossil fuel use and can help meet rising electricity demand, which is the talk of the town in many, if not most, energy and climate circles.

2. Renewable natural gas (RNG) production: After purification, methane can be converted into RNG and injected into natural gas pipelines for use in vehicles or as fuel for heating and cooking. RNG or “CNG” (compressed natural gas) offers an alternative to traditional natural gas with growing market demand. Many buses and garbage trucks in the U.S. use it; keep an eye out for “CNG” or “RNG” or other fuels that can use methane as a feedstock on vehicles around town.

3. Automated monitoring and collection optimization: Advanced technologies like automated well-tuning and continuous monitoring systems can improve gas collection efficiency by optimizing the collection process. More reading here.

To date, the overarching challenge is a familiar one, namely, who pays? And particularly in a high interest rate environment, for large-scale gas capture infrastructure projects, are natural gas prices sufficiently high and sufficiently stable and predictable (not the current commodities market environment, mind you) to justify high upfront capital expenditures? Perhaps carbon markets will mature, and renewable natural gas will command premium prices in the future, but that’s difficult to bank on, literally and figuratively. What we can bank on is monitoring technology, improving leak detection, and accountability.

Companies addressing the landfill methane challenge

Innovation in this space comes from both established waste management firms and specialized startups developing new approaches to monitoring, capture, and utilization:

Monitoring and detection

• GHGSat is expanding its satellite fleet for methane detection, adding four new satellites this year and another five by 2026.

• Carbon Mapper, which launched its Tanager-1 satellite last year, is focusing on high-resolution methane mapping and plans to launch additional satellites later this year in partnership with NASA's Jet Propulsion Laboratory, Rocky Mountain Institute, and the University of Arizona.

• MethaneSAT, launched last year by the Environmental Defense Fund (EDF) with funding from additional sourcestracks methane emissions globally. The EDF publishes data from the satellite and has provej n it csj aemissions plumes from other sources and will add the waste sector in the future. 

• Other airborne monitoring companies develop specialized equipment to survey landfills where on-foot measurements are difficult or dangerous safely. Examples include airplanes and drones, in addition to satellites.

Waste diversion and prevention

• Wasted food causes 58% of methane emissions from municipal solid waste landfills. Reducing food sent to landfills is a valuable opportunity to reduce methane emissions from landfills. This can be done by changes in consumer behavior or an increase in municipal anaerobic systems like digestors or composting. Ultimately, this is probably the most significant opportunity, not just because it’s higher upstream in the ‘(typically wasted) value chain’, but because wasted food and other organic matter are among the main drivers of methane emissions from landfills. 

• Some organics diversion and reverse logistics companies, like Divert, are scaling commercial operations, including with major grocery stores, to keep methane-generating materials like wasted food out of landfills. In some cases, they also use other inputs in anaerobic digestors, which turn them into renewable natural gas. Anaerobic digesters can also be built and operated as stand-alone infrastructure/separate businesses that then work with other entities, be they farmers, retailers, or restaurants, to source inputs.

• Here’s more reading on waste diversion and mitigation from Waste 360.

Gas capture and processing

• Major waste management companies like WM, referenced earlier, are investing in expanding landfill gas capture systems. A lot more work could be done on this front, even in the U.S. In 2023, approximately two-thirds of “GHGRP-reporting landfills*” had some gas capture system. But that’s not all U.S. landfills; it doesn’t capture all or even close to the full scope of emissions from any given landfill anywhere on Earth, nor does it represent the modal landfill management system globally, especially in developing countries.

• Other technology providers are developing more efficient collection systems that can work in challenging landfill environments or specialized well and pipe systems designed to reduce leakage from existing collection infrastructure.

• Advanced membrane separation technologies are also improving the economics of upgrading landfill gas to pipeline-quality renewable natural gas.

* According to the EPA: “The GHGRP (codified at 40 CFR Part 98 ) requires reporting of greenhouse gas (GHG) data and other relevant information from large GHG emission sources, fuel and industrial gas suppliers, and CO2 injection sites in the United States.”

Geographic and policy factors that influence emissions

GHGSat's research also revealed regional variations in landfill methane emissions across the U.S. Landfills in the southeastern U.S. had higher methane generation rates compared to other regions. The researchers theorize this could be due to the hot, wet climate that accelerates decomposition, though waste composition and regional policies likely also play roles.

States with organics diversion policies and other measures that address landfill methane emissions include California, New York, New Jersey, New Hampshire, Washington, and Oregon. These recorded lower average emissions from landfills. This points to the effectiveness of targeted policy interventions in reducing these emissions. There’s plenty more that states and even municipalities can do, of course. For instance, in 2024, Washington adopted new regulations that require gas collection and control systems specifically designed to decrease methane emissions from landfills. As to how effective these policies will be, the proof will be in the (methane emission) prevention.

Other state and local initiatives include:

• California's SB 1383 targets a 75% reduction in organic waste disposal by 2025. Granted, that’s this year, and it’s seemingly impossible the state will hit their target based on progress to date. Still, the ambition is lauded, and presumably, they’ll update it to 2030 or later. More recently and actionably, California Governor Gavin Newsom announced a $100 million satellite initiative to track and reduce methane pollution in general, with one satellite launched and 7 to go. The project will use satellite-mounted methane sensors to detect leaks from sources, like landfills and oil and gas operations in real-time.

• Several states (California, Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, and Vermont) have banned organic waste from landfills entirely. As to how well that’s working so far, well, that’s another rabbit hole.

• Many more local ordinances mandate organics diversion; wherever you live, there’s substantial opportunity for individual and collective organization and action here!

At the federal level, there are still standing regulations (for now) that help, too. For now. EPA regulations under the Clean Air Act require gas collection systems at larger landfills, though these focus more on air quality rather than atmospheric warming and climate impacts. Their reporting requirements also still allow modeling, which can yield the very underestimation of actual emissions we discussed upfront. That said, given what we’ve seen from the new administration, it’s highly likely these will be revised; much more reading on the implications of federal policy changes pursuant to landfill methane gas is available here from WasteDive. 

Turning our gaze globally, international approaches include:

• The EU lists organic waste diversion from landfills as one of its highest priorities in this policy and economic area.

• The EU also has a ‘Landfill Directive’ that started back in 1999 but is regularly updated and aims to catalyze gas collection at all major landfills. 

• Canada has proposed regulations to reduce methane emissions from landfills by about 50% by 2030 from 2019 levels, though new PM Mark Carney may change things up.

The bottom line

The growing body of data on landfill methane emissions and the technologies that enable enhanced monitoring and measurement capabilities reveal both a significant challenge and an opportunity. As is true across many sources of methane emissions and other greenhouse gasses and pollutants, we've underestimated landfill emissions from many sits and, therefore, the environmental and economic prerogatives to address them. 

Again, what makes landfill emissions particularly significant is their persistence. These are not intermittent leaks. They’re continuous sources of methane, which makes them inherently more desirable for capture. Additionally, it’s not just methane's outsized atmospheric and warming impact that makes the environmental quotient important; many studies show people living near landfills are disproportionately affected by pollution.

Fortunately, several factors are converging to make landfill methane reduction more doable:

1. Advanced monitoring technology creates opportunities to drive accountability and home in on where to prioritize mitigation efforts.

2. Renewable natural gas markets and natural gas demand in general increasingly offer a financial incentive for capture and utilization.

3. In some jurisdictions, policy frameworks are coming together to accelerate the work. 

4. Waste companies increasingly incorporate methane reduction and capture opportunities into their business strategies, even if the rate at which they do so is insufficient. 

5. The relative cost-effectiveness of landfill methane abatement makes it an intuitive area to focus on in the current political and macroeconomic environment.

For investors and technology developers, landfill methane represents a large, persistent, and often overlooked opportunity. Unlike some methane sources that require complex international coordination, landfills are fixed, identifiable, and often under local control, making them promising targets for focused mitigation efforts.

More (ideally unwasted) food for thought

Ironically, while satellites get better at monitoring methane emissions, climate change itself threatens their ability to operate safely. A new MIT study found that greenhouse gases, including methane, are causing the upper atmosphere to shrink, reducing the capacity for low-orbiting satellites to navigate safely. This could decrease the capacity of some atmospheric layers by 50%+, increasing collision risks for satellites currently in low orbit. There’s another climate feedback that makes methane emissions reduction all the more valuable, as they would decelerate warming faster than carbon dioxide emissions reductions would!

To close on a brighter note, satellites are also tracking positive trends, like the proliferation of renewable energy globally. See more from the New York Times on that front here. What do you think? Are landfills the next best frontier in methane mitigation? The lowest-hanging fruit, perhaps? We’d love to hear your thoughts!

What to do next

Thanks for reading. If you haven’t already subscribed to the Overview, do so here. And if you have others in mind who could benefit from rethinking (or starting to integrate well-informed, data-driven insights on methane into their strategy moving forward.

— This newsletter is brought to you by Lauren Singer and Nick van Osdol